if you want to know more about Threading, theres a series of posts (in the making) by Sacha Barber on Code Project. This is definitely a good read :)
The following are links to the posts:
PingBack from http://blog.a-foton.ru/2008/07/posts-about-threading-in-net/
Great read. Cant wait for the WPF doc, in particular how it works in XBAPs.